Combustion Chemistry of Jet Fuels: From Atomistic Simulations to Mechanism Development

Project completion 2018.

In recent years, there has been an increasing effort to incorporate complex reaction mechanisms in simulation of reacting flows. This need has led to the development of reaction mechanisms of various levels of detail and comprehensiveness, as it is confirmed by the increased number of published kinetic mechanisms. This number has grown by orders of magnitude over the last years, going from few tens of species for a comprehensive mechanism for the simplest hydrocarbon fuel (methane), to thousands of species for more recent detailed mechanisms [1]. These models, however, are usually developed for specific conditions, and have little chance of producing reliable extrapolations to other conditions. Attempts to correct such models lead to their increase in size and number, but all of them fail in one respect or another. Yet, for practical applications, it is not feasible to incorporate these comprehensive kinetic schemes directly in a multidimensional reactive flow simulation.

The construction of a reduced kinetic model, however, is not only limited by the simplification procedure selected, but also by the ability to obtain a complete detailed mechanism from which to reduce, which is in turn related to the difficulty of identifying all possible important reaction pathways and species. In other words, reduction depends on the fidelity of the detailed mechanism, and the comprehensiveness of a reduced mechanism cannot exceed that of a detailed mechanism from which it is reduced.

We aim to develop a novel computational procedure aimed at identifying missing reaction pathways as well as main reaction pathways to describe the combustion chemistry of JP-8, based on atomistic simulations.

This work directly supports the effort reported by Dr. Martz in his ARC project, which is currently using reduced kinetic mechanisms from available detailed kinetics present in the literature. This project will provide information on main reaction pathways that can be implemented in reduced mechanisms for use in Martz’s optimization routine.

Publications:

• Doohyun Kim, Jason Martz, and Angela Violi, “Effects of fuel physical properties on direct injection spray and ignition behavior”, Fuel 180 (2016), 481-496. doi:10.1016/j.fuel.2016.03.085
• D Kim, J Martz, A Abdul-Nour, X Yu, M Jansons, A Violi, “A six-component surrogate for emulating the physical and chemical characteristics of conventional and alternative jet fuels and their blends”, Combustion and Flame 179, pp 86-94, 2017. doi:10.1016/j.combustflame.2017.01.025
• D Kim, J Martz, A Violi, “The relative importance of fuel oxidation chemistry and physical properties to spray ignition”, SAE International Journal of Fuels and Lubricants 10, 2017-01-0269, 2017. doi:10.4271/2017-01-0269. Also presented at SAE 2017 World Congress, Detroit, MI, April 6th, 2017.
• D Kim, A Violi, A Boehman, “The Effects of Injection Timing and Injected Fuel Mass on Local Charge Conditions and Emissions for Gasoline Direct Injection Engines”, accepted to ASME 2017 Internal Combustion Engine Division Fall Technical Conference (ICEF2017-3623).
• D. Kim, A. Violi, “Hydrocarbons for the next generation jet fuel surrogates”, 10th Mediterranean Combustion Symposium, Naples, Italy, Sep. 20th, 2017.

References:

1. Herbinet, O., Pitz, W. J., and Westbrook, C. K. “Detailed Chemical Kinetic Mechanism for the Oxidation of Biodiesel Fuels Blend Surrogate”, Combustion and Flame 157, no. 5 (2010): 893–908. doi:10.1016/j.combustflame.2009.10.013